Wall outlets for electrical apparatus and the like are in widespread use, allowing convenient connection of devices such as electrical appliances, telephones, cable television receivers, and computers to electrical power mains and communication networks. In addition, similar fixtures are often attached to walls, floors, and ceilings, and are connected in like manner to electrical power and communications networks. The term “wall” herein denotes any fixed surface to which socket outlets are commonly connected and includes, without limitation, walls of a building or similar structure regardless of orientation (including, but not limited to vertical walls, as well as floors and ceilings), as well as surfaces of other structures to which socket outlets may be fixed, such as cupboards and desk tops particularly when fixedly mounted in a room. Likewise, the term “outlet” herein denotes a non-limiting instance of a fixture for attachment to a wall or other fixed structure, enabling access to in-wall wiring, commonly via faceplate panel connector. Other fixture types include, but are not limited to, wall-mounted electrical lighting and appliances, controls, switches, sensors, data devices, telephony equipment, and intercommunication devices. Outlets commonly uses in-wall dedicated cavity, but some types are surface-mount, fully installed over the wall surface.
Outlets commonly comprise two distinct parts:                (a) Faceplate. The outer part of the outlet, commonly formed of plastic and comprising a front panel accommodating a standard connector for connecting to the in-wall wiring. The front panel of the faceplate is usually decorative, being the only exposed outlet part after the installation.        (b) Wall mounting fixture. This fixture is mechanically attached to the wall on the wall inner side, and is attached to the faceplate on the wall outer side thereby fixing the outlet to the wall. Commonly, the faceplate is attached to the wall-mounting fixture be means of two screws.        
There are two principal outlet types that are in common use, depending on the style of wall construction and the opportunities consequently available for mechanically attaching fixtures to a wall and providing electrical or signal connections thereto.
One such wall mounting fixture system is the “junction box” style as illustrated in FIG. 1. The junction box style is common in North America and is used with a hollow wall construction in which a wall section 101 is held in place and supported by a support beam 103, wherein such support beams are placed at suitable intervals. Typically, wall section 101 may be a relatively thin panel of gypsum or other material (approximately one-half inch thick), and the support beam 103 is usually of wood or metal. A rectangular junction box 105 is securely fastened to the support beam 103, but may alternatively be affixed to any other suitable supporting structure. The junction box 105 has an open face 107, which is exposed through a matching opening cut into the wall section 101. Commonly, the junction box 105 is made of metal or plastic, although other suitable materials may be employed. Mounting tabs 109-a and 109-b are provided on opposing sides of the face 107 and accommodate threaded mounting holes 111-a and 111-b allowing the attachment of various electrical fixtures to the junction box 105. It is to be noted that the nominal center distance between the mounting holes 111-a and 111-b is substantially three and one-quarter (3¼) inches. Media 113 enters the junction box 105, optionally via a conduit (not shown), which connects to the junction box 105 in one of several optional apertures (not shown) in the closed faces. Media 113 can carry electrical power, telephony signals, or other signals for sensing, data, or control. Any number of media 113 can be used, and can include different combinations and configurations of electrical conductors, such as wires or coaxial cable; or non-conducting media, such as optical fiber.
FIG. 2 illustrates how a faceplate 201 (or similar fixture) is mounted according to the junction box system (wall section 101 in FIG. 1 is omitted for clarity). Screws 203-a and 203-b affix faceplate 201 to junction box 105 through the mounting holes 111-a and 111-b, respectively. Because junction box 105 is secured to the support beam 103 (or other suitable supporting structure), the faceplate 201 is thereby securely fastened in place. Faceplate 201 comprises two telephony connectors (such as RJ-11), connected to in-wall telephone-wiring, hence being part of telephone outlet. As can be seen in FIG. 2, the faceplate 201 is designed to be coupled to the wall mounting fixture 105, by means of mechanical size and rectangular shape, intended to cover all fixture 105 cavity, and holes matched for screws 203 to fit threads 111.
The second commonly used wall mounting method is the “cylindrical cavity and sleeve” style as illustrated in FIG. 3. The cylindrical cavity and sleeve style is common in Europe and the Middle East and is used with a construction in which a wall section 301 is made of solid, or substantially solid masonry or similar rigid material which is self-supporting and requires no additional structural elements for stability. A cylindrical cavity 303 is formed in the wall section 301, and an optional sleeve 305 is inserted therein from the outside. The sleeve 305 is commonly of plastic or other semi-flexible material, and typically is in the shape of a cup with a lip and closed back. The sleeve 305 may also have mounting screws (not shown) for affixing to the wall section 301.
FIG. 4 shows a prior art wall mounting fixture device 401 for the cylindrical cavity and sleeve style of wall mounting. A pair of expandable clamps 403-a and 403-b is positioned to grip the inside of the sleeve 305 (FIG. 3), or alternatively the inside of the cavity 303 if no sleeve 305 is present. Cavities are typically cylindrical with an inside diameter of approximately 5.5 centimeters, but other cavity shapes and sizes are in general also possible. Clamp 403-a can be expanded outward to engage a grip on the inside of sleeve 305 (and subsequently increase the grip strength) by tightening a screw 405, and clamp 403-b can likewise be expanded outward for this purpose by a similar screw (not shown). It is also possible to use a single expandable clamp in conjunction with a fixed clamp or similar projection that is capable of gripping the inner surface of sleeve 305 or the inside of cavity 303 if no sleeve 305 is present. Once the wall mounting sure device 401 has been secured inside the cavity 303, the faceplate (not shown) may be fastened to attachment device 401 by means of screws driven into mounting holes 407-a and 407-b. It is to be noted that the nominal center distance between mounting holes 407-a and 407-b is six (6.0) centimeters, which is approximately 2.36 inches. The faceplate is also well suited to the wall mounting fixture, being of square shape, and having screw holes suitable for affixing the faceplate into the wall mounting fixture.
It is further noted that:                the prior art wall mounting fixture device as illustrated in FIG. 4 and described herein is capable of mounting substantially all commonly-used fixtures and outlets intended for cylindrical cavity and sleeve wall mounting;        all variations in the design and configuration of such prior art wall mounting fixture devices are minor, so that all such prior art wall mounting fixture devices are substantially identical in appearance, use, and function;        wall mounting fixtures and faceplates designed for the junction box style of wall mounting are incompatible with, and cannot be mounted in, cylindrical cavity and sleeve construction using the available prior fixture attachment devices (as illustrated in FIG. 4 and as described herein); and        no means of readily mounting fixtures and outlets designed for the junction box style of wall mounting is currently available for cylindrical cavity and sleeve construction.        
All common fixture and outlet types (such as electrical power outlets, telephone jacks, and lighting fixtures) are widely available for both of the above wall mounting styles. Thus, regardless of which style of wall mounting is employed within a building, it is easy to obtain these common fixtures and outlet types for that wall mounting style.
Many specialized fixtures and outlets, however, are now becoming available for specific purposes. Non-limiting examples of such specialized fixtures and outlets include outlets for data networking, multi-media, sensors, control units, and the like. Such fixtures and outlets may not be readily available for both wall mounting styles. In general, such specialized wall mounting fixtures and faceplates tend to be available for the wall mounting style that is prevalent in the region where their most important market is located. In particular, because of the size and importance of the North American market, most such specialized wall mounting fixtures and faceplates tend to be available primarily for the junction box style of wall mounting, as illustrated in FIG. 1 and FIG. 2. In many cases, such specialized wall mounting fixtures and faceplates are not available for the cylindrical cavity and sleeve style. Where this is the case, specialized wall mounting fixtures and faceplates cannot easily be installed in buildings whose construction utilizes the cylindrical cavity and sleeve style of wall mounting without expensive and unsightly external retrofitting of junction boxes 105 within the smaller cavities 303 provided for the sleeves 305, and therefore the utility provided by such specialized wall mounting fixtures and faceplates is difficult and expensive to provide for those buildings.
There is thus a widely recognized need for, and it would be highly advantageous to have, an adapter which provides easy installation of faceplates designed for the junction box style of wall mounting in buildings whose construction utilizes the cylindrical cavity and sleeve style of wall mounting. More generally, there is a need for an adapter allowing a faceplate of one style to be installed in a cavity suitable for another distinct style. This goal is met by the present invention.